Currently, Texas Instruments Incorporated (TI) offers a number of audio amplifiers that a include DIRECTPATH™ architecture. Some features of this architecture are that an output direct current or DC blocking capacitor is not needed and that there is a negative supply rail. An example is TI's TPA6140A2, which is a class-G amplifier that uses a charge pump to invert the voltage (from a positive supply) to create a negative supply voltage so that the headphone amplifier output can be centered at 0V without the need for DC blocking capacitors. However, there are some tradeoffs associated with this architecture; namely, supplying a negative supply voltage requires several external components as well as it reduces efficiency. Additionally, these types of devices may have also need to have separate power management circuits (i.e., buck converters). Therefore, there is a need for a method or an apparatus that offers similar advantages without the drawbacks.
Some other conventional circuits are: U.S. Pat. No. 6,320,460; U.S. Pat. No. 6,753,729; U.S. Pat. No. 7,330,069; and U.S. Pat. No. 7,400,191.